1. Field of the Invention
The present invention relates to a communication technology of adapter; in particular, to a communication circuit and an adapter using the same enabling communications and data transmissions directly on a DC power line.
2. Description of Related Art
The adapter is an interface converter applied to convert different interfaces thereby allowing electronic devices of various interfaces to interconnect, or alternatively enabling the connection of an electronic device to another interface, such as a power adapter or a USB adapting apparatus etc. The power adapter is essentially employed to convert alternating current (AC) power to direct current (DC) power, or vice versa, and provide converted DC power to a connected electronic device for use. The adapter is capable of converting various AC powers (e.g., 110V or 220V) to a stable DC power such that the electronic device is applicable in different areas or countries.
Generally, a conventional power adapter is not equipped with the data transmission function; whereas, as the role of power management becoming more and more significant, notebook computers usually need to further appreciate relevant information concerning power supply thereby facilitating power management, so certain new types of power adapters are now additionally configured with the data transmission function which also improves convenience in product inspection during manufacture processes. However, the specification and design of data lines in each adapter may vary, which causes complicated communication circuit designs between the notebook computer and the adapter.
Besides, adding one extra data line may increase the number of transmission lines for the adapter from two to three. Since a 3-lined cable has a greater diameter and is less durable for bending or winding, the use of such a type of cable may be inconvenient. Also, the design for 3-line based adapters from each vendor differs, resulting in complex and impractical transmission interfaces between the notebook computer and the adapter.